JP7446738B2 - Light diffusion controller and reflective display - Google Patents

Description

The present invention relates to a light diffusion control body that can transmit and diffuse incident light within a predetermined incident angle range strongly and with low optical loss, and a reflective display body equipped with the light diffusion control body. It is.

Displays such as liquid crystal display devices, organic electroluminescence, and electronic paper are broadly classified into transmissive displays and reflective displays. The transmissive display body includes a light source such as a backlight inside thereof, and a viewer views the display illuminated from behind by the light source. On the other hand, a reflective display does not include a light source such as a backlight, and uses external indoor lighting, the sun, or the like as a light source. Incidentally, reflective display bodies also include those equipped with a system that provides a light source on the surface side of the display body to enable visibility in the form of indirect lighting when the amount of light from the outside is insufficient, such as at night. A reflective display usually includes a reflective plate inside thereof. A reflective display uses a reflector to reflect light from an external light source, and the reflected light illuminates the display.

In reflective displays, because an external light source is used, the positional relationship between the light source and the viewer is not constant. As a result, depending on the position of the light source, sufficient light does not reach the viewer, which tends to cause problems such as reduced visibility and the inability to brightly illuminate the entire display. In order to solve such problems, it is conceivable to incorporate a light diffusing plate into the display body. However, simply incorporating a general light diffusing plate may not provide sufficient diffusivity for good visibility, and attempting to achieve high diffusion may result in light loss due to stray light or backscattering. , there is a problem that image clarity is impaired. From the perspective of solving these problems, reflective displays are equipped with a light diffusion control body that can transmit and diffuse incident light within a predetermined incident angle range with high intensity and low light loss. Consideration is being given to providing a reflector between the surface on the person's side and the reflector. Due to the presence of the light diffusion control body, the light reflected by the reflection plate is appropriately diffused, and a decrease in visibility depending on the position of the light source is reduced.

As a reflective display body including the light diffusion control body as described above, Patent Document 1 includes a reflective display panel and an optical laminate disposed on the display panel, and the optical laminate includes: The optical laminate includes two or more anisotropic scattering films, at least two of the plurality of anisotropic scattering films have different transmittances in the direction of the scattering center axis, and the optical laminate includes anisotropy. Among the scattering films, the first film having a relatively high transmittance in the scattering central axis direction is a second film having a relatively low transmittance in the scattering central axis direction among the anisotropic scattering films included in the optical laminate. A display device is disclosed in which the transmittance in the direction of the central scattering axis is four times or more compared to that of the prior art.

Patent No. 5749960

Incidentally, in recent years, the scope of use of reflective displays such as liquid crystal display devices and electronic paper has expanded, and as a result, higher visibility is required, or performance that allows visibility even under poorer light conditions is required. It is becoming more and more sought after. As a result, conventional reflective displays such as those disclosed in Patent Document 1 are no longer able to meet the required performance, and there is a need for a light diffusion controller that can achieve better visibility.

The present invention has been made in view of the above circumstances, and aims to provide a light diffusion control body capable of realizing a display body with excellent visibility, and a reflective display body with excellent visibility. purpose.

In order to achieve the above object, the present invention first provides at least a light diffusion control layer having a regular internal structure including a plurality of regions having a relatively high refractive index within a region having a relatively low refractive index. In the light diffusion control body having two layers, the first light diffusion control layer and the second light diffusion control layer, which are two of the light diffusion control layers, each have one side of the first light diffusion control layer and the other side of the light diffusion control layer. Provided is a light diffusion control body, characterized in that the minimum haze value measured when irradiating light beams sequentially at an incident angle of -70° to 70° with the normal direction as 0° is 35% or more. (Invention 1).

The light diffusion control body according to the above invention (invention 1) is provided with the first light diffusion control layer and the second light diffusion control layer each having the above-mentioned minimum haze value, thereby appropriately controlling light. It becomes possible to diffuse it. Therefore, in a reflective display body equipped with the light diffusion control body, it becomes possible to effectively utilize even light rays incident from a more oblique direction, resulting in excellent visibility.

In the above invention (invention 1), it is preferable that the central diffusion axis of the first light diffusion control layer and the central diffusion axis of the second light diffusion control layer are at different angles (invention 2).

In the above inventions (Inventions 1 and 2), the regular internal structure in at least one of the first light diffusion control layer and the second light diffusion control layer includes the It is preferable that the film has a column structure in which a plurality of columnar objects having a relatively high refractive index are arranged in a row in the film thickness direction (Invention 3).

Second, the present invention provides a reflective display comprising the light diffusion control body (inventions 1 to 3) and a reflecting plate provided on one side of the light diffusion control body ( Invention 4).

According to the light diffusion control body according to the present invention, it is possible to manufacture a display body, particularly a reflective display body, having excellent visibility.

FIG. 2 is a sectional view of a light diffusion control body according to an embodiment of the present invention. FIG. 2 is a perspective view schematically showing an example of a regular internal structure (column structure) of a light diffusion control layer in an embodiment of the present invention. FIG. 1 is a cross-sectional view of a reflective display body including a light diffusion control body according to an embodiment of the present invention. It is a figure which shows the result of Test Example 1 (angle-bending haze measurement of a light-diffusion control layer). It is a figure which shows a part of result of Test Example 2 (diffusion brightness distribution measurement of a light-diffusion control layer). It is a figure which shows a part of result of Test Example 2 (diffusion brightness distribution measurement of a light diffusion control layer). FIG. 7 is a diagram showing a part of the results of Test Example 3 (diffuse luminance distribution measurement of reflective display sample). It is a figure which shows a part of result of Test Example 3 (diffuse luminance distribution measurement of reflective display body sample). FIG. 7 is a diagram showing a part of the results of Test Example 3 (diffuse luminance distribution measurement of reflective display sample). FIG. 7 is a diagram showing a part of the results of Test Example 3 (diffuse luminance distribution measurement of reflective display sample). It is a figure which shows the graph obtained from the result of Test Example 3 (diffuse luminance distribution measurement of reflective display body sample). FIG. 4 is a diagram showing the results of Test Example 4 (evaluation of visibility of reflective display sample).

Embodiments of the present invention will be described below.
[Light diffusion control body]
FIG. 1 shows a cross-sectional view of a light diffusion control body according to an embodiment of the present invention. The light diffusion control body 1 shown in FIG. 1 includes at least two light diffusion control layers each having a regular internal structure including a plurality of regions having a relatively high refractive index within a region having a relatively low refractive index. . Here, the above-mentioned regular internal structure refers to an internal structure in which a plurality of regions with a relatively high refractive index are arranged with a predetermined regularity in a region with a relatively low refractive index (for example, a light diffusion control When looking at a cross section obtained by cutting the light diffusion control layer along a plane parallel to the layer surface and at a position where the regular internal structure is present, the refractive index is relatively This refers to an internal structure in which regions with a relatively high refractive index are repeatedly arranged at the same pitch along at least one direction within the above-mentioned cross section in a region with a relatively high refractive index.

In particular, the light diffusion control body 1 shown in FIG. 1 includes a first light diffusion control layer 11 and a second light diffusion control layer 12 laminated on one side of the first light diffusion control layer 11. It has been prepared. Note that the light diffusion control body 1 according to the present embodiment may further include a light diffusion control layer other than the first light diffusion control layer 11 and the second light diffusion control layer 12, or may further include a light diffusion control layer other than the first light diffusion control layer 11 and the second light diffusion control layer 12. It may further include a layer other than the above layer. Further, the form of the light diffusion control body 1 is not particularly limited as long as it includes the first light diffusion control layer 11 and the second light diffusion control layer 12, and for example, it may be incorporated into a display body. It may be in the form of a general member, and is particularly preferably in the form of a film, that is, a light diffusion control film.

In the light diffusion control body 1 according to the present embodiment, the first light diffusion control layer 11 and the second light diffusion control layer 12 each have an angle of −70° with respect to one surface thereof, with the normal direction of the surface being 0°. The minimum value of the haze value measured when the light beam is sequentially irradiated at an incident angle of ° to 70 ° is 35% or more. The light diffusion control body 1 according to the present embodiment includes at least two light diffusion control layers having a minimum haze value of 35% or more, so that light rays incident on the light diffusion control body 1 at a predetermined angle can be It becomes possible to moderately diffuse and transmit the light. As a result, when a reflective display body is manufactured using the light diffusion control body 1 according to the present embodiment, the incident angle of the incident light (normal to the display surface of the reflective display body) is Even if the angle between the angle and the incident light is larger, the incident light will effectively reach the viewer. As a result, the viewer can perceive the display brighter, that is, excellent visibility is achieved. Such excellent visibility is similarly achieved in a transmissive display body manufactured using the light diffusion control body 1 according to this embodiment.

From the viewpoint of realizing better visibility, the minimum value of the haze value described above in at least one of the first light diffusion control layer 11 and the second light diffusion control layer 12 (preferably in both layers) is 40. % or more, more preferably 50% or more, particularly preferably 60% or more, and even more preferably 65% or more.

Further, the maximum value of the haze value described above is preferably 80% or more in at least one of the first light diffusion control layer 11 and the second light diffusion control layer 12 (preferably in both layers), It is more preferably 85% or more, particularly preferably 90% or more, and even more preferably 95% or more. In at least one of the first light diffusion control layer 11 and the second light diffusion control layer 12 (preferably in both layers), the maximum value of the haze value described above is as described above, so that the viewer can , it becomes easier to reach a clearer display.

The above minimum and maximum haze values can be obtained by a variable angle haze measurement using a variable angle haze meter or the like, and the details of the measurement method are as described in the test examples described below.

In the light diffusion control body 1 according to the present embodiment, the difference in haze value between the first light diffusion control layer 11 and the second light diffusion control layer 12 is preferably less than 50 points, particularly 30 points. It is preferably at most 10 points, more preferably at most 10 points, and even more preferably at most 5 points. When the difference in haze value is less than 50 points, the first light diffusion control layer 11 and the second light diffusion control layer 12 tend to have the minimum haze value described above. Note that the lower limit value of the difference in haze value is not particularly limited, and may be, for example, 0.1 point or more, particularly 0.5 point or more, and even 1% point or more. . Note that the haze value in the difference in haze value is the haze value measured when each light diffusion control layer is irradiated with a light beam at an incident angle of 0°.

In the light diffusion control body 1 according to the present embodiment, it is preferable that the central diffusion axis of the first light diffusion control layer 11 and the central diffusion axis of the second light diffusion control layer 12 are at different angles. Thereby, the light diffusion control body 1 according to the present embodiment can more easily disperse light rays incident at a predetermined angle. Therefore, in the reflective display body including the light diffusion control body 1 according to the present embodiment, incident light having a larger incident angle can be easily reflected toward the viewer, that is, better visibility can be achieved. Ru. In addition, the above-mentioned diffusion central axis refers to an axis around which the diffusion characteristics are approximately symmetrical, and can be estimated based on the diffusion performance ascertained by measurement of the variable angle haze of the light diffusion control layer, etc. The detailed measurement method is as described in the test example described below.

In addition, from the viewpoint of further achieving excellent visibility, the angle between the central diffusion axis of the first light diffusion control layer 11 and the central diffusion axis of the second light diffusion control layer 12 should be 1° or more. The angle is preferably at least 5°, particularly preferably at least 10°. In this way, since the angle between the central diffusion axes is greater than or equal to the above range, the light diffusion control body 1 according to the present embodiment can more easily disperse the light rays incident at a predetermined angle.

On the other hand, the angle between the central diffusion axis of the first light diffusion control layer 11 and the central diffusion axis of the second light diffusion control layer 12 is preferably 40° or less, and particularly preferably 30° or less. The angle is preferably 20° or less. When the angle between the central diffusion axes is within the above range, the range in which the emitted light is effectively diffused tends to overlap between the first light diffusion control layer 11 and the second light diffusion control layer 12. As a result, it becomes easier to achieve better visibility.

In the light diffusion control body 1 according to the present embodiment, a light beam is irradiated onto one side of the first light diffusion control layer 11 from an incident angle that causes the incident light to be most strongly diffused, and is thereby transmitted to the other side. Ratio between the maximum value of the light intensity of the diffused light and the maximum value of the light intensity of the diffused light similarly measured for the second light diffusion control layer 12 (ratio obtained by dividing the larger value by the smaller value) ) is preferably less than 4 times, more preferably 3.5 times or less, further preferably 3 times or less, and even more preferably 2 times or less, 1.4 Most preferably, it is less than twice that. When the ratio is less than 4 times, the first light diffusion control layer 11 and the second light diffusion control layer 12 tend to have the minimum haze value described above. On the other hand, the lower limit of the ratio is not particularly limited, and may be, for example, 1.00 times or more, particularly 1.01 times or more, and even 1.05 times or more. . Note that the maximum value of the light intensity of the diffused light can be obtained, for example, by measuring the diffuse brightness distribution of the light diffusion control layer using a diffuse brightness distribution measuring device, and the details of the measurement method are described in the test example described below. It is as follows.

1. Structure of Light Diffusion Control Layer The first light diffusion control layer 11 and the second light diffusion control layer 12 included in the light diffusion control body according to the present embodiment have a relatively low refractive index in a region with a relatively low refractive index. There are no particular limitations on the haze value as long as it has a regular internal structure with a plurality of regions with high haze values and the minimum haze value described above. Note that when the light diffusion control body according to the present embodiment further includes a light diffusion control layer other than the first light diffusion control layer 11 and the second light diffusion control layer 12, this additional light diffusion control layer is It is not particularly limited as long as it has a regular internal structure with a plurality of regions having a relatively high refractive index within a region having a relatively low refractive index.

The first light diffusion control layer 11, the second light diffusion control layer 12, and the further light diffusion control layer include a high refractive index component and a low refractive index component having a lower refractive index than the high refractive index component. It is preferable that the composition for a light diffusion control layer is cured. In particular, it is preferable that the high refractive index component and the low refractive index component each have one or two polymerizable functional groups. By using such a composition for a light diffusion control layer, it becomes easy to form the above-mentioned regular internal structure well, and the first light diffusion control layer 11 and the second light diffusion control layer 12 can be formed. In this case, the haze value can be easily adjusted, and as a result, the minimum haze value described above can be easily achieved.

(1) High refractive index component Preferred examples of the high refractive index component include (meth)acrylic esters containing an aromatic ring, particularly preferably (meth)acrylic esters containing a plurality of aromatic rings. It will be done. Examples of (meth)acrylic esters containing multiple aromatic rings include biphenyl (meth)acrylate, naphthyl (meth)acrylate, anthracyl (meth)acrylate, benzylphenyl (meth)acrylate, and (meth)acrylate. Biphenyloxyalkyl acrylate, naphthyloxyalkyl (meth)acrylate, anthracyloxyalkyl (meth)acrylate, benzylphenyloxyalkyl (meth)acrylate, etc. Some of these are halogen, alkyl, alkoxy, and alkyl halide. Examples include those substituted by, etc. Among these, biphenyl (meth)acrylate is preferred from the viewpoint of easily forming a good regular internal structure, and specifically, o-phenylphenoxyethyl acrylate, o-phenylphenoxyethoxyethyl acrylate, etc. are preferred. In addition, in this specification, (meth)acrylic acid means both acrylic acid and methacrylic acid. The same applies to other similar terms.

The weight average molecular weight of the high refractive index component is preferably 2,500 or less, particularly preferably 1,500 or less, and even more preferably 1,000 or less. Further, the weight average molecular weight of the high refractive index component is preferably 150 or more, particularly preferably 200 or more, and even more preferably 250 or more. When the weight average molecule of the high refractive index component is within the above range, it becomes easier to form a light diffusion control layer having a desired regular internal structure, and the first light having the minimum haze value described above can be easily formed. This makes it easier to form the diffusion control layer 11 and the second light diffusion control layer 12. Note that the weight average molecular weight in this specification is a value measured by gel permeation chromatography (GPC) in terms of standard polystyrene.

The refractive index of the high refractive index component is preferably 1.45 or more, more preferably 1.50 or more, particularly preferably 1.54 or more, and even more preferably 1.56 or more. is preferred. Further, the refractive index of the high refractive index component is preferably 1.70 or less, particularly preferably 1.65 or less, and even more preferably 1.59 or less. When the refractive index of the high refractive index component is within the above range, it becomes easy to form a light diffusion control layer having a desired regular internal structure, and the first light diffusion control layer having the above-mentioned minimum haze value can be formed. This makes it easier to form the control layer 11 and the second light diffusion control layer 12. In addition, the refractive index in this specification means the refractive index of a predetermined component before curing the composition for a light diffusion control layer, and the refractive index is measured according to JIS K0062:1992. It is.

The content of the high refractive index component in the composition for a light diffusion control layer is preferably 25 parts by mass or more, particularly preferably 40 parts by mass or more, based on 100 parts by mass of the low refractive index component. Furthermore, it is preferably 50 parts by mass or more. Further, the content of the high refractive index component in the composition for a light diffusion control layer is preferably 400 parts by mass or less, particularly preferably 300 parts by mass or less, based on 100 parts by mass of the low refractive index component. The amount is preferably 200 parts by mass or less. When the content of the high refractive index component is within these ranges, the regular internal structure of the formed light diffusion control layer has desired regions derived from the high refractive index component and regions derived from the low refractive index component. It will exist at a rate of . As a result, it becomes easier to form a light diffusion control layer having a desired regular internal structure, and the first light diffusion control layer 11 and second light diffusion control layer 12 having the above-mentioned minimum haze value. It becomes easy to form.

(2) Low refractive index component Preferred examples of the low refractive index component include urethane (meth)acrylate, (meth)acrylic polymer having (meth)acryloyl group in the side chain, (meth)acryloyl group-containing silicone resin, Examples include unsaturated polyester resins, but it is particularly preferable to use urethane (meth)acrylate.

The urethane (meth)acrylate is preferably formed from (a) a compound containing at least two isocyanate groups, (b) polyalkylene glycol, and (c) hydroxyalkyl (meth)acrylate.

Preferred examples of the above-mentioned (a) compound containing at least two isocyanate groups include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate, 1, Aromatic polyisocyanates such as 4-xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, alicyclic polyisocyanates such as isophorone diisocyanate (IPDI), hydrogenated diphenylmethane diisocyanate, and their biuret forms, isocyanurate forms, and adduct forms (e.g., xylylene diisocyanate), which are reactants with low-molecular active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil. trifunctional adducts) and the like. Among these, cycloaliphatic polyisocyanates are preferred, and cycloaliphatic diisocyanates containing only two isocyanate groups are particularly preferred.

Preferred examples of the above-mentioned polyalkylene glycol (b) include polyethylene glycol, polypropylene glycol, polybutylene glycol, polyhexylene glycol, etc. Among them, polypropylene glycol is preferred.

The weight average molecular weight of the polyalkylene glycol (b) is preferably 2,300 or more, particularly preferably 4,300 or more, and even more preferably 6,300 or more. The weight average molecular weight of the polyalkylene glycol (b) is preferably 19,500 or less, particularly preferably 14,300 or less, and even more preferably 12,300 or less.

Preferred examples of the above-mentioned (c) hydroxyalkyl (meth)acrylate include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 2-hydroxybutyl (meth)acrylate. ) acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and the like. Among these, it is preferable to use 2-hydroxyethyl methacrylate from the viewpoint of reducing the polymerization rate of the resulting urethane (meth)acrylate and forming a predetermined regular internal structure more efficiently.

Synthesis of urethane (meth)acrylate using the above-mentioned components (a) to (c) can be carried out according to a conventional method. At this time, from the viewpoint of efficiently synthesizing urethane (meth)acrylate, the blending ratio of components (a) to (c) is determined in terms of molar ratio: (a) component: (b) component: (c) component = The ratio is preferably 1 to 5:1:1 to 5, particularly preferably 1 to 3:1:1 to 3, and even more preferably 2:1:2.

The weight average molecular weight of the low refractive index component is preferably 3,000 or more, particularly preferably 5,000 or more, and even more preferably 7,000 or more. Further, the weight average molecular weight of the low refractive index component is preferably 20,000 or less, particularly preferably 15,000 or less, and even more preferably 13,000 or less. When the weight average molecular weight of the low refractive index component is within the above range, it becomes easier to form a light diffusion control layer having a desired regular internal structure, and the first light having the above-mentioned minimum haze value can be easily formed. This makes it easier to form the diffusion control layer 11 and the second light diffusion control layer 12.

The refractive index of the low refractive index component is preferably 1.59 or less, more preferably 1.50 or less, particularly preferably 1.49 or less, and even more preferably 1.48 or less. is preferred. Further, the refractive index of the low refractive index component is preferably 1.30 or more, particularly preferably 1.40 or more, and even more preferably 1.46 or more. When the refractive index of the low refractive index component is within the above range, it becomes easier to form a light diffusion control layer having a desired regular internal structure, and the first light diffusion control layer having the above-mentioned minimum haze value can be formed. This makes it easier to form the control layer 11 and the second light diffusion control layer 12.

(3) Other components The composition for a light diffusion control layer described above may contain other additives in addition to the high refractive index component and the low refractive index component. Other additives include, for example, polyfunctional monomers (compounds having three or more polymerizable functional groups), photopolymerization initiators, antioxidants, ultraviolet absorbers, antistatic agents, polymerization accelerators, and polymerization inhibitors. , infrared absorbers, plasticizers, diluting solvents, and leveling agents.

Among the additives mentioned above, it is also preferable that the composition for a light diffusion control layer contains a photopolymerization initiator. When the composition for a light diffusion control layer contains a photopolymerization initiator, it becomes easy to efficiently form a light diffusion control layer having a desired regular internal structure.

Examples of photopolymerization initiators include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexylphenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]- 2-morpholino-propan-1-one, 4-(2-hydroxyethoxy)phenyl-2-(hydroxy-2-propyl)ketone, benzophenone, p-phenylbenzophenone, 4,4-diethylaminobenzophenone, dichlorobenzophenone, 2- Methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzyl Examples include dimethyl ketal, acetophenone dimethyl ketal, p-dimethylamine benzoate, oligo[2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propane], and the like. These may be used alone or in combination of two or more.

When using a photopolymerization initiator, the content of the photopolymerization initiator in the composition for a light diffusion control layer is 0.2 parts by mass with respect to 100 parts by mass of the total amount of the high refractive index component and the low refractive index component. It is preferably at least 0.5 parts by mass, particularly preferably at least 0.5 parts by mass, and even more preferably at least 1 part by mass. Further, the content of the photopolymerization initiator is preferably 20 parts by mass or less, particularly preferably 15 parts by mass or less, based on 100 parts by mass of the total amount of the high refractive index component and the low refractive index component. The amount is preferably 10 parts by mass or less. By setting the content of the photopolymerization initiator in the composition for a light diffusion control layer within the above range, the light diffusion control layer can be easily formed efficiently.

(4) Preparation of composition for light diffusion control layer The composition for light diffusion control layer is prepared by uniformly adding the above-mentioned high refractive index component and low refractive index component, and if desired, other additives such as a photopolymerization initiator. It can be adjusted by mixing.

During the above mixing, stirring may be performed while heating to a temperature of 40 to 80° C. to obtain a uniform composition for a light diffusion control layer. Further, a diluting solvent may be added and mixed so that the resulting composition for a light diffusion control layer has a desired viscosity.

2. Regular internal structure of light diffusion control layer As described above, the light diffusion control layer in this embodiment includes a plurality of regions having a relatively high refractive index within a region having a relatively low refractive index. It has a regular internal structure. More specifically, the light diffusion control layer in this embodiment has a plurality of regions having a relatively high refractive index in a region having a relatively low refractive index with a predetermined length in the film thickness direction. It has an elongated regular internal structure. Note that the regular internal structure here is one in which a region with a relatively high refractive index extends in the film thickness direction, meaning that one phase exists within the other phase without any clear regularity. It is distinguished from a phase-separated structure formed by a sea-like structure, and a sea-island structure formed by a nearly spherical island component existing in a sea component.

A more specific example of the above-mentioned regular internal structure is a column structure in which a plurality of columnar objects with a relatively high refractive index are arranged in a forest in the film thickness direction in a region with a relatively low refractive index. Can be mentioned. In the first light diffusion control layer 11 and the second light diffusion control layer 12 in this embodiment, it is preferable to have a column structure as a regular internal structure from the viewpoint of easily achieving the minimum value of the haze value described above. preferable.

(1) Column structure FIG. 2 is a perspective view schematically showing the column structure described above. As shown in FIG. 2, in the column structure 113, a plurality of columnar objects 112 having a relatively high refractive index stand in a forest in the thickness direction, and the surrounding area fills a region 114 with a relatively low refractive index. ing. Although the columnar objects 112 are depicted as existing in the entire thickness direction of the column structure 113 in FIG. The object 112 may not exist.

When the light incident on the light diffusion control layer having such a column structure 113 falls within a predetermined incident angle range, the light is emitted from the light diffusion control layer while being strongly diffused with a predetermined opening angle. On the other hand, if the incident light is incident at an angle outside the above incident angle range, it will either be transmitted without being diffused, or it will be emitted with weaker diffusion than in the case of incident light within the incident angle range. . Note that when the contrast body is arranged parallel to the surface of the light diffusion control layer, the diffused light generated by the column structure 113 has a circular shape or a substantially circular shape (such as an elliptical shape) that spreads in any direction.

In the column structure 113, it is preferable that the difference between the refractive index of the columnar object 112 having a relatively high refractive index and the refractive index of the region 114 having a relatively low refractive index is 0.01 or more, particularly 0.01 or more. It is preferably .05 or more, and more preferably 0.1 or more. When the difference is 0.01 or more, effective diffusion can be performed. Note that the upper limit of the above difference is not particularly limited, and may be, for example, 0.3 or less.

The columnar objects 112 described above preferably have a structure in which the diameter increases from one surface to the other surface of the light diffusion control layer. The columnar object 112 having such a structure can easily change the traveling direction of light parallel to the axial direction of the columnar object, compared to a columnar object whose diameter does not change substantially from one surface to the other. This allows the light diffusion control layer to effectively diffuse light.

Further, the maximum value of the diameter in a cross section when the columnar object 112 is cut along a plane horizontal to the axial direction is preferably 0.1 μm or more, particularly preferably 0.5 μm or more, and The thickness is preferably 1 μm or more. Further, the maximum value is preferably 15 μm or less, particularly preferably 10 μm or less, and even more preferably 5 μm or less. When the maximum value of the diameter is within the above range, the light diffusion control layer can effectively diffuse light. Note that the cross-sectional shape of the columnar object 112 when cut along a plane perpendicular to the axial direction is not particularly limited, but is preferably, for example, a circle, an ellipse, a polygon, an irregular shape, or the like.

In the column structure 113, the distance between adjacent columnar objects 112 is preferably 0.1 μm or more, particularly preferably 0.5 μm or more, and even more preferably 1 μm or more. Further, the distance is preferably 15 μm or less, particularly preferably 10 μm or less, and even more preferably 5 μm or less. When the distance between adjacent columnar objects 112 is within the above range, the light diffusion control layer can effectively diffuse light.

Further, in the column structure 113, the columnar objects 112 may be arranged in a forest horizontally with respect to the thickness direction of the light diffusion control layer, or may be arranged in a forest at a constant inclination angle. The inclination angle when the trees stand at a constant inclination angle, that is, the acute angle between the axis of the columnar objects 112 of the column structure 113 and the normal to the surface of the light diffusion control layer, is 1° or more. The angle is preferably 5° or more, and more preferably 10° or more. Further, the angle is preferably 50° or less, particularly preferably 40° or less, and even more preferably 30° or less. Since the columnar objects 112 are inclined within the above range, the light diffusion control layer including such a column structure 113 can diffuse the transmitted light while biasing it in a desired direction.

Note that the above dimensions, predetermined angles, etc. related to the regular internal structure of the column structure 113 can be measured by observing the cross section of the column structure 113 using an optical digital microscope.

(2) Modified example of column structure The regular internal structure of the light diffusion control layer in this embodiment may be a structure obtained by modifying the column structure 113 described above. For example, the light diffusion control layer may have an internal structure in which the columnar objects 112 in the column structure 113 described above are bent midway in the thickness direction of the light diffusion control layer. Further, the light diffusion control layer may have a column structure 113 having two or more columnar regions having different inclination angles in the thickness direction of the light diffusion control layer.

3. Method for manufacturing a light diffusion control body The method for manufacturing a light diffusion control body according to the present embodiment includes, for example, the first light diffusion control layer 11, the second light diffusion control layer 12, and, if desired, further light diffusion. It can be obtained by separately forming other layers such as a control layer and then stacking them in a desired order. Another example of the manufacturing method is to form the second light diffusion control layer 12 directly on the first light diffusion control layer 11 after forming the first light diffusion control layer 11. You can also do it.

The method of forming the first light diffusion control layer 11, the second light diffusion control layer 12, and the further light diffusion control layer is not particularly limited, and can be formed by a conventionally known method. For example, after applying the above-described composition for a light diffusion control layer on one side of a process sheet to form a coating film, one side of a release sheet (especially the release side ). Subsequently, a light diffusion control layer can be formed by irradiating the coating film with active energy rays and curing it through the process sheet or release sheet. In this way, by laminating the release sheet on the coating film, a gap between the release sheet and the process sheet is maintained, the coating film is suppressed from being crushed, and a light diffusion control layer with a uniform thickness is formed. It becomes easier to do.

Examples of the above-mentioned coating methods include knife coating, roll coating, bar coating, blade coating, die coating, and gravure coating. Further, the composition for a light diffusion control layer may be diluted with a solvent if necessary.

The coating film is irradiated with active energy rays in different ways depending on the regular internal structure to be formed. Such irradiation can be performed by a conventionally known method. For example, when forming the above-described column structure, the coating film is irradiated with parallel light having a high degree of parallelism.

Note that the active energy rays refer to electromagnetic waves or charged particle beams that have energy quantum, and specifically include ultraviolet rays and electron beams. Among active energy rays, ultraviolet rays are particularly preferred because they are easy to handle.

When forming a column structure using ultraviolet rays as active energy rays, the irradiation conditions are preferably such that the peak illuminance at the coating surface is 0.1 to 10 mW/cm ² . In addition, the peak illumination intensity here means the measured value at the part where the active energy ray irradiated to the coating film surface shows the maximum value. Further, it is preferable that the cumulative amount of light on the surface of the coating film is 5 to 200 mJ/cm ² .

In addition, in order to complete curing more reliably, after curing using parallel light or band-shaped light as described above, normal active energy rays (processing to convert them into parallel light or band-shaped light are performed). It is also preferable to irradiate with active energy rays or scattered light.

4. Use of Light Diffusion Control Body The use of the light diffusion control body 1 according to this embodiment is not particularly limited, and it can be used in the same manner as conventional light diffusion control bodies. In particular, the light diffusion control body 1 according to this embodiment is suitable for use in manufacturing a reflective display.

FIG. 3 shows a cross-sectional view of an example of a reflective display 2 manufactured using the light diffusion control body 1 according to this embodiment. The reflective display 2 includes the light diffusion control body 1 according to the present embodiment and a reflection plate 21 provided on one side of the light diffusion control body 1.

Note that the reflective display body 2 may include layers and members other than the light diffusion control body 1 and the reflection plate 21. For example, a display panel such as a liquid crystal may be provided between the light diffusion control body 1 and the reflection plate 21. Alternatively, the reflective display body 2 may have a configuration in which the light diffusion control body 1 is provided on one side of the display panel, and a reflective plate 21 may be provided as one of the members constituting the display panel. .

Examples of the reflective display body 2 include electronic devices such as reflective liquid crystal display devices, electronic paper, electrophoretic displays, MEMS displays, and solid crystal displays. In addition to such electronic devices, the reflective display body 2 may be one in which display contents are printed on paper, a resin film, a metal plate, or the like. In this case, paper, a resin film, a metal plate, etc. may serve as the reflecting plate 21, or a paper with printing for display, A resin film or the like may be provided.

Further, the light diffusion control body 1 according to the present embodiment can also be used for manufacturing a transmission type display such as a transmission type liquid crystal display device or an organic EL display.

The light diffusion control body 1 according to the present embodiment includes the first light diffusion control layer 11 and the second light diffusion control layer 12 each having the minimum haze value described above, so that backscattered light, stray light, etc. It becomes possible to diffuse light appropriately while preventing light loss. As a result, excellent visibility is achieved in the display (especially the reflective display 2) manufactured using the light diffusion control body 1.

The embodiments described above are described to facilitate understanding of the present invention, and are not described to limit the present invention. Therefore, each element disclosed in the above embodiments is intended to include all design changes and equivalents that fall within the technical scope of the present invention.

Hereinafter, the present invention will be explained in more detail with reference to examples, but the scope of the present invention is not limited to these examples.

[Preparation Example 1] (Light diffusion control layer A)
(1) Preparation of composition for light diffusion control layer Polyether urethane with a weight average molecular weight of 9,900 obtained by reacting polypropylene glycol, isophorone diisocyanate, and 2-hydroxyethyl methacrylate as a low refractive index component 60 parts by mass of o-phenylphenoxyethoxyethyl acrylate with a molecular weight of 268 as a high refractive index component and 2-hydroxy-2- as a photopolymerization initiator to 40 parts by mass of methacrylate (solid content equivalent; the same applies hereinafter). After adding 8 parts by mass of methyl-1-phenylpropan-1-one, heating and mixing were performed at 80° C. to obtain a composition for a light diffusion control layer.

(2) Formation of light diffusion control layer The obtained composition for a light diffusion control layer was applied to one side of a long polyethylene terephthalate sheet as a process sheet to form a coating film. Next, a release sheet (manufactured by Lintec, product name: "SP-PET381130", thickness: 38 μm, made by treating one side of a polyethylene terephthalate film with a silicone release agent) was applied to the opposite side of the coating film from the process sheet. ) was laminated on the peeled surface.

The resulting laminate consisting of the release sheet, the coating film, and the process sheet was placed on a conveyor. At this time, the surface of the laminate on the release sheet side was the upper side, and the longitudinal direction of the laminate was parallel to the flow direction of the conveyor. Then, an ultraviolet spot parallel light source (manufactured by JATEC Corporation) whose center beam parallelism was controlled within ±3° was installed on the conveyor on which the laminate was placed. At this time, the light source was installed so that it could irradiate parallel light in the normal direction of the surface of the laminate on the release sheet side.

Thereafter, while operating ^the conveyor and moving the laminate, parallel light with a parallelism of ² degrees or less ( The coating film in the laminate was cured by irradiation with ultraviolet rays (from a high-pressure mercury lamp having a main peak wavelength of 365 nm and other peaks at 254 nm, 303 nm, and 313 nm) to form a light diffusion control layer A with a thickness of 60 μm. . As a result, a laminate was obtained in which the process sheet, the light diffusion control layer A (thickness: 60 μm), and the release sheet were laminated in this order.

In addition, when microscopic observation of the cross section of the formed light diffusion control layer A was performed, a column structure consisting of a plurality of columnar objects standing in the entire thickness direction was formed inside the light diffusion control layer A. It was confirmed that there is. That is, the ratio of column structure regions extending in the thickness direction inside the obtained light diffusion control layer A was 100%. Moreover, it was confirmed that the above-mentioned columnar objects were parallel to the thickness direction of the light diffusion control layer A (inclination angle of 0°). In this specification, the inclination angle is expressed as 0° vertically upward in the normal direction of the film surface, plus in the conveyor traveling direction, and minus in the opposite direction.

In addition, the peak illuminance and cumulative light intensity described above were measured by installing a UV METER (manufactured by Eye Graphics, product name: "Eye Ultraviolet Integrated Illuminance Meter UVPF-A1") equipped with a light receiver at the position of the above coating film. It is something. The thickness of the light diffusion control layer A was measured using a constant pressure thickness measuring device (manufactured by Takara Seisakusho Co., Ltd., product name: "Techlock PG-02J").

[Preparation Example 2] (Light diffusion control layer B)
The composition for a light diffusion control layer obtained in the same manner as in step (1) of Preparation Example 1 was applied to one side of a long polyethylene terephthalate sheet as a process sheet to form a coating film. The resulting laminate consisting of the coating film and the process sheet was placed on a conveyor. At this time, the surface of the laminate facing the coating film was placed on the upper side, and the longitudinal direction of the laminate was made to be parallel to the flow direction of the conveyor. Then, an ultraviolet spot parallel light source (manufactured by JATEC Corporation) whose center beam parallelism was controlled within ±3° was installed on the conveyor on which the laminate was placed. At this time, the light source was installed so that it could irradiate parallel light in a direction inclined by 10 degrees to the flow direction of the conveyor with respect to the normal direction of the surface of the laminate on the coating film side.

Thereafter, while operating ^the conveyor and moving the laminate, parallel light with a parallelism of ² degrees or less ( Ultraviolet rays from a high-pressure mercury lamp having a main peak wavelength of 365 nm and other peaks at 254 nm, 303 nm, and 313 nm were irradiated.

Next, on the opposite side of the coating film from the process sheet, a release sheet (manufactured by Lintec, product name: "SP-PET381130", thickness: 38 μm) in which one side of a polyethylene terephthalate film was treated with a silicone release agent was applied. ) was laminated on the peeled surface. The resulting laminate consisting of the release sheet, coating film, and process sheet was placed on a conveyor in the same manner as above. Subsequently, an ultraviolet spot collimated light source was installed on the conveyor in the same manner as above. Then, while the conveyor was operated and the laminate was moved, scattered light was irradiated on the surface of the coating film under conditions of a peak illuminance of 11.0 mW/cm ² and an integrated light amount of 32.0 mJ/cm ² .

As described above, the coating film in the laminate was cured to form a light diffusion control layer B having a thickness of 90 μm. As a result, a laminate was obtained in which the process sheet, light diffusion control layer B (thickness: 90 μm), and release sheet were laminated in this order.

Note that the ratio of column structure regions extending in the thickness direction inside the obtained light diffusion control layer B was 10%. Further, it was confirmed that the above-mentioned columnar objects were inclined by about 7 degrees in the direction of movement of the conveyor with respect to the thickness direction of the light diffusion control layer B (inclination angle +7 degrees).

[Preparation Example 3] (Light diffusion control layer C)
The process sheet, the light diffusion control layer C (thickness: 120 μm), and the release sheet were laminated in this order in the same manner as in Production Example 2, except that the thickness of the formed light diffusion control layer was changed to 120 μm. A laminate was obtained.

Note that the ratio of column structure regions extending in the thickness direction inside the obtained light diffusion control layer C was 30%.

[Preparation example 4] (Light diffusion control layer D)
The process sheet, the light diffusion control layer D (thickness: 140 μm), and the release sheet were laminated in this order in the same manner as in Production Example 2, except that the thickness of the formed light diffusion control layer was changed to 140 μm. A laminate was obtained.

Note that the ratio of column structure regions extending in the thickness direction inside the obtained light diffusion control layer D was 40%.

[Preparation Example 5] (Light diffusion control layer E)
The process sheet, the light diffusion control layer E (thickness: 160 μm), and the release sheet were laminated in this order in the same manner as in Production Example 2 except that the thickness of the formed light diffusion control layer was changed to 160 μm. A laminate was obtained.

Note that the proportion of column structure regions extending in the thickness direction inside the obtained light diffusion control layer E was 50%.

[Preparation Example 6] (Light diffusion control layer F)
The process sheet, the light diffusion control layer F (thickness: 185 μm), and the release sheet were laminated in this order in the same manner as in Production Example 2 except that the thickness of the formed light diffusion control layer was changed to 185 μm. A laminate was obtained.

Note that the proportion of column structure regions extending in the thickness direction inside the obtained light diffusion control layer F was 60%.

[Example 1]
The process sheet and release sheet were peeled off and removed from the laminates produced in Production Example 1 and Production Example 4, respectively, to obtain a light diffusion control layer A and a light diffusion control layer D. Then, the surface of the light diffusion control layer D as the second light diffusion control layer opposite to the surface irradiated with the ultraviolet rays is placed on the side of the light diffusion control layer A as the first light diffusion control layer that is irradiated with ultraviolet rays. A light diffusion control body was obtained by stacking them so that their longitudinal directions (direction of movement of the conveyor) coincided with each other.

Furthermore, aluminum was vapor-deposited to a thickness of 300 nm on the surface of the first light diffusion control layer (light diffusion control layer A) side of the light diffusion control body and on the surface of the reflection plate (a polyethylene terephthalate film with a thickness of 100 μm). A reflective display sample was obtained by stacking the reflective surfaces of the display panel and the reflective surface of the display panel.

[Example 2]
The process sheet and the release sheet were peeled off and removed from the laminate produced in Production Example 5 to obtain a light diffusion control layer E, and the process was carried out in the same manner as in Example 1, except that this was used as the second light diffusion control layer. , samples of a light diffusion control body and a reflective display body were obtained.

[Example 3]
The process sheet and release sheet were peeled off and removed from the laminate produced in Production Example 6 to obtain a light diffusion control layer F, and the process was carried out in the same manner as in Example 1, except that this was used as the second light diffusion control layer. , samples of a light diffusion control body and a reflective display body were obtained.

[Comparative example 1]
The second light diffusion control layer was not provided, and a single layer of the first light diffusion control layer (light diffusion control layer A) was used as the light diffusion control body. Furthermore, a reflective display sample was obtained in the same manner as in Example 1 except that the light diffusion controller was used.

[Comparative example 2]
The process sheet and the release sheet were peeled off and removed from the laminate produced in Production Example 2 to obtain light diffusion control layer B, and this was carried out in the same manner as in Example 1, except that this was used as the second light diffusion control layer. , samples of a light diffusion controller and a reflective display were obtained.

[Comparative example 3]
The process sheet and release sheet were peeled off and removed from the laminate produced in Production Example 3 to obtain a light diffusion control layer C, and the process was carried out in the same manner as in Example 1, except that this was used as the second light diffusion control layer. , samples of a light diffusion control body and a reflective display body were obtained.

[Test Example 1] (Variation haze measurement of light diffusion control layer)
For the light diffusion control layers A to F produced in Production Examples 1 to 6, the haze value ( %) was measured.

Specifically, in the single light diffusion control layer obtained by peeling and removing the process sheet and release sheet from the laminates obtained in Preparation Examples 1 to 6, the surface opposite to the surface irradiated with ultraviolet rays during manufacture was It was attached to one side of an alkali glass plate (thickness: 1.1 mm) to obtain a laminate. The laminate was installed in the variable angle haze meter so that the distance from the integrating sphere opening to the measurement light arrival position was 62 mm, and the alkali-free glass side faced the light source. Next, the change in haze value (%) was measured by rotating the longitudinal direction of the light diffusion control layer (transport direction during production) with the width direction of the light diffusion control layer at the above-mentioned arrival position as the rotation axis. That is, by changing only the inclination angle of the light diffusion control layer, the incident angle of the measurement light with respect to the light diffusion control layer was changed, and the haze value (%) was measured for each incident angle. Note that the incident angle at which the measurement light is normal to the laminate is 0°, and the rotational direction in which the traveling direction side of the light diffusion control layer in the longitudinal direction (transportation direction during fabrication) approaches the light source is -70°. Measurements were made in the range of ~70°. The details of the measurement conditions were as follows.
Light source: C light source Measurement diameter: φ18mm
Integrating sphere opening diameter: φ25.4mm

The measurement results are shown in FIG. 4. Note that in FIG. 4, the horizontal axis represents the incident angle, and the vertical axis represents the measured value. Furthermore, among the measured haze values (%), the value when the incident angle was 0°, the minimum value, and the maximum value were specified. These results are shown in Table 1.

Furthermore, from the results shown in FIG. 4, the central diffusion axis of the light diffusion control layer was identified as follows. In the graph of FIG. 4, when the incident angle is changed from a negative value to a positive value, the haze value rises and then decreases to the original level again. Here, we calculate the average value of the incident angle at which the haze value first reaches its maximum during the rise and the incident angle at which the haze value reaches its maximum immediately before the haze value decreases to its original level, and then diffuse this value. It was set as the central axis. In addition, in the graph of FIG. 4, there are two incident angles where the haze value is maximum, and between them there is one incident angle where the haze value is minimum, but it is difficult to specify the central axis of diffusion. In this case, the angle of incidence at which this minimum value is reached is not considered. Table 1 also shows the diffusion center axis obtained in this way.

[Test Example 2] (Measurement of diffused brightness distribution of light diffusion control layer)
For the light diffusion control layers A to F produced in Preparation Examples 1 to 6, the diffuse luminance was measured using a diffuse luminance distribution measuring device (manufactured by Suga Test Instruments Co., Ltd., product name "Variable Colorimeter VC-2"). The distribution was measured.

Specifically, in the single light diffusion control layer obtained by peeling and removing the process sheet and release sheet from the laminates obtained in Preparation Examples 1 to 6, the surface opposite to the surface irradiated with ultraviolet rays during manufacture was A laminate was obtained by attaching it to one side of an alkali glass plate (thickness: 1.1 mm). The measurement light is irradiated onto the non-alkali glass side surface of the laminate from the direction of the central diffusion axis, and the light intensity of the diffused light transmitted to the other surface (the surface on the light diffusion control layer side) is measured. , measurements were taken sequentially while moving the receiver. At this time, the light receiver is rotated around the width direction of the light diffusion control layer that includes the emission point of the diffused light (a direction perpendicular to the same plane as the longitudinal direction), and is maintained at an equal distance from the emission point. However, it was moved while facing the surface of the light diffusion control layer. The movement was performed such that the angle between the line segment connecting the emission point and the light receiver and the normal line passing through the emission point (light receiver angle) was from −45° to 45°. In addition, the value of the angle is such that the angle at which the light receiver is proximal to the traveling direction side of the light diffusion control layer in the longitudinal direction (transfer direction during fabrication) is positive, and the angle at which the light receiver is distal is negative. represents. A C light source was used as the light source.

On the other hand, as a reference, a reference value of light intensity was measured without setting up a measurement target and with the light receiver angle fixed at 0° (the measurement light was directly irradiated onto the light receiver). Then, the ratio of the light intensity of each light diffusion control layer measured as described above to the reference value (percentage with the reference value as 100%) was calculated. The results are shown in Figures 5-1 and 5-2. Note that in FIGS. 5-1 and 5-2, the horizontal axis represents the receiver angle, and the vertical axis represents the light intensity (%). Further, FIG. 5-1 shows the results for the light diffusion control layers A, D, E, and F, and FIG. 5-2 shows the results for the light diffusion control layers B and C.

Furthermore, the maximum value of the obtained light intensity (%) was determined. The maximum values are shown in Table 1. Furthermore, the ratio of the maximum values of the light diffusion control layers A to F with respect to the maximum value of the light diffusion control layer A was calculated. The results are also shown in Table 1.

[Test Example 3] (Measurement of diffused luminance distribution of reflective display sample)
Regarding the reflective display samples equipped with light diffusion control bodies obtained in Examples and Comparative Examples, using a diffuse luminance distribution measuring device (manufactured by Suga Test Instruments Co., Ltd., product name "Variable colorimeter VC-2"), The diffuse brightness distribution was measured.

Specifically, the surface of the reflective display sample on the light diffusion control body side is irradiated with a light beam at an angle of incidence of 10 degrees with respect to the normal to the surface (incident angle of 10 degrees). The light intensity of the diffused light reflected by the display sample was sequentially measured while moving the light receiver. At this time, the light receiver is rotated around the width direction of the light diffusion control layer that includes the emission point of the diffused light (a direction perpendicular to the same plane as the longitudinal direction), and is maintained at an equal distance from the emission point. However, it was moved while facing the light diffusion control layer. The movement was performed such that the angle between the line segment connecting the emission point and the light receiver and the normal line passing through the emission point (light receiver angle) was from −45° to 0°. In addition, the value of the angle is such that the angle at which the light receiver is proximal to the traveling direction side of the light diffusion control layer in the longitudinal direction (transfer direction during fabrication) is positive, and the angle at which the light receiver is distal is negative. represents. Note that a C light source was used as the light source.

On the other hand, as a reference, a standard white component plate was installed as a measurement target, and a reference value of light intensity was measured with the receiver angle fixed at -45°. Then, the ratio of the light intensity of each light reflective display sample measured as described above to the reference value (percentage with the reference value as 100%) was calculated. The results are shown in Figure 6-1. Note that in FIG. 6-1, the horizontal axis represents the receiver angle, and the vertical axis represents the light intensity (%). Furthermore, Table 2 shows the light intensity (%) when the receiver angle is 0°.

Furthermore, the incident angle was changed to 20° (receiver angle: -45° to 10°), 30° (receiver angle: -45° to 20°), and 40° (receiver angle: -45° to 30°). The diffused luminance distribution was measured in the same manner as above. These measurement results are shown in Figures 6-2, 6-3, and 6-4. Table 2 also shows the light intensity (%) when the receiver angle is 0° in each case where the incident angle is changed to 20°, 30°, and 40°.

In addition, based on the light intensity (%) when the receiver angle is 0° obtained as described above, the minimum value (%) of the bending angle haze value and the light intensity (%) for each incident angle are calculated. I created a graph showing the relationship. The graph is shown in FIG. In this graph, the horizontal axis is the minimum value (%) of the variable angle haze value of the second light diffusion control layer in each example, and the vertical axis is the light intensity (%) when the receiver angle is 0°. Note that for Comparative Example 1 in which the second light diffusion control layer was not provided, the minimum value (%) of the angular haze value of the second light diffusion control layer was "0%". Also, points with the same angle of incidence are connected by line segments.

[Test Example 4] (Evaluation of visibility of reflective display sample)
The reflective display samples manufactured in Example 1, Example 2, and Comparative Example 3 were arranged on a support stand so that the surface facing the light diffusion control body faced upward. Then, the light beam of the desk light was irradiated onto the surface at an incident angle (incidence angle of 10 degrees) such that the angle with the normal to the surface was 10 degrees. Then, the brightness of the reflective display sample was visually observed from a position in front of the surface, and the reflective display sample was photographed from the same position using a digital still camera. The obtained image is shown in FIG. Further, the incident angle was changed to 35°, and visual confirmation was performed in the same manner as above, and photography was performed using a digital still camera. The obtained image is shown in FIG.

As is clear from FIG. 8, when the incident angle was 10°, the reflective display samples according to Example 1, Example 2, and Comparative Example 3 were able to be visually recognized almost equally brightly. On the other hand, when the incident angle was 35°, the reflective display samples according to Examples 1 and 2 could be seen brightly, whereas the reflective display samples according to Comparative Example 3 It was visible in the dark.

As shown in Table 2, in the reflective display sample equipped with the light diffusion control body according to the example, when the incident angle is 10° to 30°, light is emitted with sufficient light intensity in the front direction. It can be seen that it was possible to reflect In particular, in the case of an incident angle of 30°, the light intensity of the reflective display sample according to the comparative example was around 100% or a value smaller than that, whereas the reflective display sample according to the example It can be seen that the display sample was able to reflect light in the front direction with a light intensity that greatly exceeded 100%. These results also coincided with the visual visibility evaluation results shown in FIG.

Note that when the incident angle was 40°, none of the reflective display samples according to the comparative example was able to reflect light toward the front direction, whereas Examples 2 and 3 It can be seen that the reflective display sample was able to reflect light in the front direction.

Furthermore, according to the graph in FIG. 8, when the incident angle is 10° and 20°, the light with a light intensity of 100% or more does not depend on the minimum value of the variable angle haze value in the second light diffusion control layer. However, when the incident angle is 30°, the light intensity is 100% or more when the minimum value of the angle-varying haze value in the second light diffusion control layer is about 35% or more. It can be seen that the light can be reflected.

The light diffusion control body of the present invention is suitably used for manufacturing display bodies, particularly reflective display bodies.

1...Light diffusion control body 11...First light diffusion control layer 12...Second light diffusion control layer 112...Columnar object with relatively high refractive index 113...Column structure 114...Region 2 with relatively low refractive index ...Reflective display body 21...Reflector plate

Claims (2)

A light diffusion control body comprising at least two light diffusion control layers having a regular internal structure including a plurality of regions having a relatively high refractive index in a region having a relatively low refractive index,
The at least two light diffusion control layers are stacked on each other,
The at least two light diffusion control layers are obtained by curing a composition for a light diffusion control layer containing a high refractive index component and a low refractive index component having a lower refractive index than the high refractive index component. The high refractive index component is a (meth)acrylic acid ester containing a plurality of aromatic rings, and the low refractive index component is a urethane (meth)acrylate,
The first light diffusion control layer and the second light diffusion control layer, which are two of the light diffusion control layers, are each at an angle of −70° to one surface with the normal direction of the surface being 0°. The minimum value of the haze value measured when sequentially irradiating the light beam at an incident angle of 70° is 35% or more,
The central diffusion axis of the first light diffusion control layer and the central diffusion axis of the second light diffusion control layer are at different angles,
The regular internal structure in both the first light diffusion control layer and the second light diffusion control layer includes a plurality of columnar structures having a relatively high refractive index in the region having a relatively low refractive index. It has a column structure in which objects are arranged in a row in the film thickness direction.
The difference in haze value between the first light diffusion control layer and the second light diffusion control layer is 0.1 point or more and 5 points or less,
The haze value related to the difference is a haze value measured when a light beam is irradiated on each of the first light diffusion control layer and the second light diffusion control layer at an incident angle of 0°.
A light diffusion control body characterized by: The light diffusion control body according to claim 1,
A reflective display body comprising: a reflection plate provided on one side of the light diffusion control body.

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